Thanks for your feedback. We will prepare a V2 patch according to your advice.

Best wishes, Tuo Li

On 2021/8/10 21:38, Chen, Guchun wrote:

[Public]

Thanks for your patch.

I suggest moving the check of function pointer dc->clk_mgr->funcs->get_clock earlier, and return early if it's NULL, as if it's NULL, it's meaningless to continue the clock setting.

.... if (!dc->clk_mgr || !dc->clk_mgr->funcs->get_clock) return DC_FAIL_UNSUPPORTED_1;

dc->clk_mgr->funcs->get_clock(dc->clk_mgr, context, clock_type, &clock_cfg); ....

Regards, Guchun

-----Original Message----- From: amd-gfx amd-gfx-bounces@lists.freedesktop.org On Behalf Of Tuo Li Sent: Tuesday, August 10, 2021 5:20 PM To: Wentland, Harry Harry.Wentland@amd.com; Li, Sun peng (Leo) Sunpeng.Li@amd.com; Deucher, Alexander Alexander.Deucher@amd.com; Koenig, Christian Christian.Koenig@amd.com; Pan, Xinhui Xinhui.Pan@amd.com; airlied@linux.ie; daniel@ffwll.ch; Cyr, Aric Aric.Cyr@amd.com; Lei, Jun Jun.Lei@amd.com; Zhuo, Qingqing Qingqing.Zhuo@amd.com; Siqueira, Rodrigo Rodrigo.Siqueira@amd.com; Lee, Alvin Alvin.Lee2@amd.com; Stempen, Vladimir Vladimir.Stempen@amd.com; isabel.zhang@amd.com; Lee, Sung Sung.Lee@amd.com; Po-Yu Hsieh Paul Paul.Hsieh@amd.com; Wood, Wyatt Wyatt.Wood@amd.com Cc: amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org; baijiaju1990@gmail.com; Tuo Li islituo@gmail.com; TOTE Robot oslab@tsinghua.edu.cn Subject: [PATCH] drm/display: fix possible null-pointer dereference in dcn10_set_clock()

The variable dc->clk_mgr is checked in: if (dc->clk_mgr && dc->clk_mgr->funcs->get_clock)

This indicates dc->clk_mgr can be NULL. However, it is dereferenced in: if (!dc->clk_mgr->funcs->get_clock)

To fix this possible null-pointer dereference, check dc->clk_mgr before dereferencing it.

Reported-by: TOTE Robot oslab@tsinghua.edu.cn Signed-off-by: Tuo Li islituo@gmail.com

---

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c index c545eddabdcc..3a7c7c7efa68 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c +++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c @@ -3635,7 +3635,7 @@ enum dc_status dcn10_set_clock(struct dc *dc, dc->clk_mgr->funcs->get_clock(dc->clk_mgr, context, clock_type, &clock_cfg);

• if (!dc->clk_mgr->funcs->get_clock)

• if (dc->clk_mgr && !dc->clk_mgr->funcs->get_clock) return DC_FAIL_UNSUPPORTED_1;

  if (clk_khz > clock_cfg.max_clock_khz)

-- 2.25.1